SYMBBANCHID.E. 67 



Abdomen usually keeled. No adipose dorsal. 

 Scales on body, none on head. Pyloric append- 

 ages numerous Clupeidae. 



VII. No pseudobranchiae. Margin of upper jaw 

 mostly formed by premaxillaries, behind and 

 parallel to which are the maxillaries. No scales 

 or barbels. Abdomen rounded. Dorsal opposite 

 anal. No adipose fin. Few pyloric caeca ; large 

 air-bladder. The ova fall into the abdominal 



cavity before exclusion Galaxidae. 



VIII. Pseudobranchiae absent. Margin of upper 

 jaw formed by premaxillaries and maxillaries. 

 Opercular apparatus incomplete ; a parieto-nias- 

 toid cavity on either side, leading into the 

 interior of the skull. A single rayed dorsal fin ; 

 a long anal. Head and body scaled. Two 



pyloric appendages Notopteridae. 



IX. Pseudobranchiae well developed. Margin of 

 upper jaw formed by^ premaxillaries. Opercular 



Sieces sometimes incomplete. No oarbels. 

 ill -openings very wide. Scales present or 

 absent. Adipose dorsal present Scopelidae. 



X. Pseudobranchiae absent. Margin of upper jaw 



formed by premaxillaries. Barbels absent. 

 Teeth in both jaws, and in superior and inferior 

 pharyngeals. One spineless dorsal in posterior 

 half of body. Air-bladder simple Cyprinodontidae. 



XI. Pseudobranchise glandular. Margin of upper 

 jaw formed by premaxillaries and maxillaries. 

 Lower pharyngeals united. No adipose dorsal. 

 Scales present. Air-bladder, when present, des- 

 titute of pneumatic duct Scombresocidae. 



Family I. SYMBEANCHID^. 



Gill-openings confluent into a single slit, which is situated on 

 the abdominal surface. Gills well developed or rudimentary. Body 

 elongated. The humeral arch may or may not be attached to the 

 skull. Margin of the upper jaw formed by tbe premaxillaries, the 

 maxillaries being internal and parallel to them. Barbels absent. 

 Palatine teeth, when present, in a single row or a narrow band. 

 Vertical fins rudimentary, in the form of mere folds of skin, and no 

 paired fins. Scales, if present, minute. Vent far behind the 

 head. An accessory breathing-sac present or absent. Air-bladder 

 absent. Ribs present. Stomach destitute of a blind eac. No 

 pyloric appendages. Ovaries with oviducts. 



The families Symbranchidw and Murcenidce belong to the Apodcs 

 of many authors. The first is fairly represented in the fresh waters 

 on the continent of India, whereas the latter is more numerous in 



F2 



